U.S. patent application number 11/476610 was filed with the patent office on 2007-02-01 for methods for handing over, by double transmission of data, a call involving a mobile node in a micromobility or macromobility situation in an ip communication network using hierarchical mobility management.
This patent application is currently assigned to ALCATEL. Invention is credited to Laurence Gras, Jean-Pierre Rombeaut.
Application Number | 20070025323 11/476610 |
Document ID | / |
Family ID | 35457714 |
Filed Date | 2007-02-01 |
United States Patent
Application |
20070025323 |
Kind Code |
A1 |
Rombeaut; Jean-Pierre ; et
al. |
February 1, 2007 |
Methods for handing over, by double transmission of data, a call
involving a mobile node in a micromobility or macromobility
situation in an IP communication network using hierarchical
mobility management
Abstract
A call handover method for an Internet Protocol communication
network using hierarchical mobility management comprising a
mobility anchor point connected to first and second access routers
and to a home agent of a mobile node having first local and
regional care-of addresses and communicating with another node
consists in, if the mobile node detects the second access router:
i) communicating the address prefix of the second access router to
the mobile node in order for it to construct a second local care-of
address, ii) communicating the second local care-of address, the
first regional care-of address and an information bit having a
value indicating double temporary addressing to the anchor point in
order for it to store the second local care-of address in
corresponding relationship to the first regional care-of address
and then forward packets addressed to the mobile node to the first
and second access routers, and iii) disconnecting the mobile node
from the first access node and then deleting the first local
care-of address of the mobile node stored at the anchor point in
order to forward packets that are addressed to it to the mobile
node via the home agent equipment, the anchor point and the second
access router.
Inventors: |
Rombeaut; Jean-Pierre;
(Maubeuge, FR) ; Gras; Laurence; (Bures Sur
Yvette, FR) |
Correspondence
Address: |
SUGHRUE MION, PLLC
2100 PENNSYLVANIA AVENUE, N.W.
SUITE 800
WASHINGTON
DC
20037
US
|
Assignee: |
ALCATEL
|
Family ID: |
35457714 |
Appl. No.: |
11/476610 |
Filed: |
June 29, 2006 |
Current U.S.
Class: |
370/349 |
Current CPC
Class: |
H04W 8/26 20130101; H04W
8/085 20130101; H04W 36/0011 20130101; H04W 40/00 20130101; H04L
45/50 20130101; H04W 80/04 20130101 |
Class at
Publication: |
370/349 |
International
Class: |
H04J 3/24 20060101
H04J003/24 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 30, 2005 |
FR |
0551834 |
Claims
1. A method of handing over a call involving a mobile equipment
that has set up an IP call with a communication equipment via an
agent equipment providing a home agent function for said mobile
equipment, an anchor point and a first radio access equipment
belonging to an Internet Protocol communication network using
hierarchical mobility management, said mobile equipment having
first local and regional care-of addresses stored at said anchor
point, which method consists in carrying out the following
combination of steps if said mobile equipment while roaming detects
a second access equipment connected to said anchor point: i)
communicating the address prefix of said second access equipment to
said mobile equipment in order for it to construct a second local
care-of address on the basis thereof, ii) communicating said second
local care-of address, said first regional care-of address and an
information bit having a value indicating double temporary
addressing to said anchor point in order for it to store the second
local care-of address in corresponding relationship to the first
regional care-of address and then forward packets addressed to said
mobile equipment to the first and second access equipments
designated by said first and second local care-of addresses, and
iii) disconnecting said mobile equipment from the first access
equipment and then deleting the first local care-of address of the
mobile equipment stored at said anchor point in order to forward
packets that are addressed to it to the mobile equipment via said
home agent equipment, said anchor point and said second access
equipment.
2. A method according to claim 1, wherein in the step i) said
second access equipment sends said mobile equipment a router
advertisement type message including at least its address
prefix.
3. A method according to claim 1, wherein in the step i) said
mobile equipment constructs its second local care-of address by
means of a stateless autoconfiguration procedure.
4. A method according to claim 1, wherein in the step ii) said
mobile equipment communicates said second local care-of address,
said first regional care-of address and said information bit to
said anchor point by means of a local binding update type
message.
5. A method according to claim 4, wherein in the step ii) said
anchor point sends a local binding acknowledgement type message to
said mobile equipment after storing said second local care-of
address in corresponding relationship to said first regional
care-of address.
6. A method according to claim 1, wherein in the step iii) said
mobile equipment sends a local binding update type message to said
anchor point including its first local and regional care-of
addresses and requesting it to delete the record corresponding
thereto so that it retains only the record of the second local
care-of address in corresponding relationship to the first regional
care-of address.
7. A method according to claim 6, wherein in the step iii) said
anchor point sends a local binding acknowledgement type message to
said mobile equipment after deleting the record of said second
local care-of address in corresponding relationship to said first
regional care-of address.
8. A method of handing over a call involving a mobile equipment
that has set up an IP call with a communication equipment via an
agent equipment providing a home agent function for said mobile
equipment, a first anchor point and a first radio access equipment
belonging to an Internet Protocol communication network using
hierarchical mobility management, said mobile equipment having
first local and regional care-of addresses stored at said first
anchor point and said home agent equipment, which method consists
in carrying out the following combination of steps if said mobile
equipment while roaming detects a second access equipment connected
to a second anchor point of said network itself connected to said
home agent equipment: i) communicating the address prefix of said
second access equipment to said mobile equipment in order for it to
construct second local and regional care-of addresses on the basis
thereof, ii) communicating said second local and regional care-of
addresses to said first anchor point in order for it to store the
second local care-of address in corresponding relationship to the
second regional care-of address, iii) communicating said second
regional care-of address, an IP home address of said mobile
equipment and an information bit having a value indicating double
temporary addressing to said home agent equipment in order for it
to store said second regional care-of address in corresponding
relationship to said IP home address and then forward packets
addressed to said mobile equipment to the first and second anchor
points designated by said first and second regional care-of
addresses stored in corresponding relationship to said IP home
address, and iv) disconnecting said mobile equipment from the first
access equipment and then deleting the first regional care-of
address of the mobile equipment stored at said home agent equipment
in corresponding relationship to said IP home address in order to
forward packets that are addressed to it to the mobile equipment
via said home agent equipment, said second anchor point and said
second access equipment.
9. A method according to claim 8, wherein in the step i) said
second access equipment sends said mobile equipment a router
advertisement type message including at least its address
prefix.
10. A method according to claim 8, wherein in the step i) said
mobile equipment constructs its second local and regional care-of
addresses by means of a stateless autoconfiguration procedure.
11. A method according to claim 8, wherein in the step ii) said
mobile equipment communicates said second local and regional
care-of addresses to said second anchor point by means of a binding
update type message.
12. A method according to claim 11, wherein in the step ii) said
second anchor point sends a binding acknowledgement type message to
said mobile equipment after storing said second local care-of
address in corresponding relationship to said second regional
care-of address.
13. A method according to claim 8, wherein in the step iii) said
mobile equipment sends said second regional care-of address, IP
home address and information bit to said home agent equipment by
means of a binding update type message.
14. A method according to claim 13, wherein in the step iii) said
home agent equipment sends a binding acknowledgement type message
to the mobile equipment after storing said second regional care-of
address in corresponding relationship to said IP home address and
said first regional care-of address.
15. A method according to claim 8, wherein in the step iv) said
mobile equipment sends to said home agent equipment a binding
update message including its first regional care-of address and its
IP home address and requesting it to delete the record of said
first regional care-of address so that it retains only the record
of the second regional care-of address in corresponding
relationship to the IP home address.
16. A method according to claim 15, wherein in the step iv) said
home agent equipment sends to said first mobile equipment a binding
acknowledgement type message after deleting the record of said
first regional care-of address.
17. A mobility anchor point for an Internet protocol communication
network using hierarchical mobility management adapted to implement
a portion of a handover method according to claim 1.
18. A home agent equipment for an Internet protocol communication
network using hierarchical mobility management adapted to implement
a portion of a handover method according to claim 1.
19. A method according to claim 1, wherein said communication
network is an MIPv6 type communication network using hierarchical
mobility management.
20. A home agent equipment according to claim 18, wherein said
communication network is an MIPv6 type communication network.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is based on French Patent Application No.
0551834 filed 30/06/2005, the disclosure of which is hereby
incorporated by reference thereto in its entirety, and the priority
of which is hereby claimed under 35 U.S.C. .sctn.119.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention relates to Internet Protocol (IP)
communication networks supporting hierarchical mobility management
(i.e. comprising hierarchically organized points of presence (also
known as home agents (HA)) and anchor points (also known as
mobility anchor points (MAP))), and more precisely handover (call
transfer) between access equipments of these networks involving at
least one mobile (communication) equipment.
[0004] In the present context the expression "IP network" refers to
a federation of subsets of IP networks (or IP subnetworks)
interconnected by access equipments forming nodes, such as access
routers.
[0005] In the present context, the expression "IP network using
hierarchical mobility management" refers to an IP network in which
calls between a mobile equipment (or node) and a communication
equipment are effected via an agent equipment providing the home
agent (HA) (or native) function for the mobile equipment, for
example a home (or native) router, a mobility anchor point (MAP),
for example a router, and a radio access equipment, for example an
access router.
[0006] In the present context, the expression "mobile communication
equipment" and the expression "mobile node" refer to any mobile (or
portable) radio communication equipment (referred to hereinafter as
a mobile equipment) capable of connecting to its home (sub)network
(subnet) (or native subnetwork) or other subnetworks, referred to
as remote (or external or foreign) subnetworks or visited networks,
in order to exchange data in the form of signals with another
communication equipment or with a subnetwork, for example, mobile
telephones, laptop computers or personal digital assistants (PDA)
equipped with a communication module.
[0007] 2. Description of the Prior Art
[0008] Each mobile equipment that connects to an IP network has an
IP home address (or IP native or permanent address) that
corresponds to the prefix of the home (sub)network to which it is
usually connected. When a mobile equipment is connected to its home
network, data packets (or datagrams) sent to it are sent directly
to its IP home address using a standard hop-by-hop type routing
protocol. When the mobile equipment is roaming and wishes to
connect to a remote (or external) subnetwork, it must configure
itself with local and regional care-of (or complementary)
addresses, known as care-of addresses, constructed from an address
prefix supplied by the IP network, for example by means of a
standard IPv6 mechanism, such as stateful or stateless
autoconfiguration. These care-of addresses must be associated with
the IP home address at the time of a binding update procedure
effected between the mobile equipment and its home agent.
[0009] The person skilled in the art knows that there exist in the
IP networks cited above IP mobility protocols, for example MIPv6,
for ensuring that a mobile equipment can be contacted at any time
and for ensuring the continuity of mobile equipment calls in
progress, in particular during phases of transfer (handover)
between access routers. Thus these protocols enable mobile
equipments to maintain their connection to the Internet during
handover and to continue to communicate with other equipments after
changing their access (or attachment) point. However, they
necessitate protocol operations and exchanges of signaling that
introduce a phase during which the mobile equipment is no longer
able to send or receive data packets (or datagrams).
[0010] A fast version FMIPv6 of MIPv6 has been proposed to limit
the duration of this phase in which it is impossible to exchange
packets, but only for handover between first and second access
equipments connected to the same mobility anchor point, i.e.
micromobility situations (in which mobility is limited to a single
site (or anchor point) and is therefore characterized by local
movements). It is therefore not applicable to handovers between
first and second access equipments connected to first and second
mobility anchor points, respectively, i.e. macromobility
situations. Furthermore, FMIPv6 can only redirect a portion of the
traffic which, on the one hand, does not limit sufficiently the
duration of the phase in which it is impossible to exchange packets
during a handover and, on the other hand, can lead to loss of
packets.
[0011] Thus an object of the invention is to remedy the drawback
cited above.
SUMMARY OF THE INVENTION
[0012] To this end the invention proposes a first method of handing
over a call involving at least one mobile equipment (in a
micromobility situation) between first and second radio access
equipments connected to the same mobility anchor equipment (or
point) itself connected to a home agent equipment providing the
home (or native) agent function for the mobile equipment in an
Internet Protocol (IP) communication network using hierarchical
mobility management.
[0013] This first method consists in carrying out the following
combination of steps if the mobile equipment while roaming detects
a second radio access equipment connected to the anchor point each
time the mobile equipment has established an IP call with another
communication equipment via the home agent equipment, the anchor
point and a first radio access equipment:
[0014] i) communicating the address prefix of the second access
equipment to the mobile equipment in order for it to construct a
second local care-of address on the basis thereof,
[0015] ii) communicating the second local care-of address, the
first regional care-of address and an information bit having a
value indicating double temporary addressing to the anchor point in
order for it to store the second local care-of address in
corresponding relationship to the first regional care-of address
and then forward packets addressed to the mobile equipment to the
first and second access equipments designated by the first and
second local care-of addresses, and
[0016] iii) disconnecting the mobile equipment from the first
access equipment and then deleting the first local care-of address
of the mobile equipment stored at the anchor point in order to
forward packets that are addressed to it to the mobile equipment
via the home agent equipment, the anchor point and the second
access equipment.
[0017] The first method of the invention may have other features
and in particular, separately or in combination:
[0018] in the step i) the second access equipment can send the
mobile equipment a router advertisement type message including at
least its address prefix (or network address) and preferably the
address of the anchor point to which it is connected;
[0019] in the step i) the mobile equipment can construct its second
local care-of address by means of a stateless autoconfiguration
procedure;
[0020] in the step ii) the mobile equipment can communicate the
second local care-of address, the first regional care-of address
and the information bit to the anchor point by means of a local
binding update type message. The anchor point can then send a local
binding acknowledgement type message to the mobile equipment after
storing the second local care-of address in corresponding
relationship to the first regional care-of address;
[0021] in the step iii) the mobile equipment can send a local
binding update type message to the anchor point including its first
local and regional care-of addresses and requesting it to delete
the record corresponding thereto so that it retains only the record
of the second local care-of address in corresponding relationship
to the first regional care-of address. The anchor point can then
send a local binding acknowledgement type message to the mobile
equipment after deleting the record of the second local care-of
address in corresponding relationship to the first regional care-of
address.
[0022] The invention also proposes a second method of handing over
a call involving at least one mobile equipment (in a macromobility
situation) between first and second radio access equipments
connected to respective first and second mobility anchor equipments
(or points) themselves connected to the same home agent equipment
providing the home (or native) agent function for the mobile
equipment in an Internet Protocol (IP) communication network using
hierarchical mobility management.
[0023] The second method consists in carrying out the following
combination of steps if the mobile equipment while roaming detects
the second access equipment connected to the second anchor point
itself connected to the home agent equipment each time the mobile
equipment has established an IP call with another communication
equipment via the home agent equipment, the anchor point and a
first radio access equipment:
[0024] i) communicating the address prefix of the second access
equipment to the mobile equipment in order for it to construct
second local and regional care-of addresses on the basis
thereof,
[0025] ii) communicating the second local and regional care-of
addresses to the first anchor point in order for it to store the
second local care-of address in corresponding relationship to the
second regional care-of address,
[0026] iii) communicating the second regional care-of address, an
IP home address of the mobile equipment and an information bit
having a value indicating double temporary addressing to the home
agent equipment in order for it to store the second regional
care-of address in corresponding relationship to the IP home
address and then forward packets addressed to the mobile equipment
to the first and second anchor points designated by the first and
second regional care-of addresses stored in corresponding
relationship to the IP home address, and
[0027] iv) disconnecting the mobile equipment from the first access
equipment and then deleting the first regional care-of address of
the mobile equipment stored at the home agent equipment in
corresponding relationship to the IP home address in order to
forward packets that are addressed to it to the mobile equipment
via the home agent equipment, the second anchor point and the
second access equipment.
[0028] The second method of the invention may have other features
and in particular, separately or in combination:
[0029] in the step i) the second access equipment can send via each
of its interfaces the mobile equipment a router advertisement type
message including at least its address prefix (or network address)
and preferably the address of the anchor point to which it is
connected;
[0030] in the step i) the mobile equipment can construct its second
local and regional care-of addresses by means of a stateless
autoconfiguration procedure;
[0031] in the step ii) the mobile equipment can communicate the
second local and regional care-of addresses to the second anchor
point by means of a binding update type message. The second anchor
point can then send a binding acknowledgement type message to the
mobile equipment after storing the second local care-of address in
corresponding relationship to the second regional care-of
address;
[0032] in the step iii) the mobile equipment can send the second
regional care-of address, IP home address and information bit to
the home agent equipment by means of a binding update type message.
The home agent equipment can then send a binding acknowledgement
type message to the mobile equipment after storing the second
regional care-of address in corresponding relationship to the IP
home address and the first regional care-of address;
[0033] in the step iv) the mobile equipment can send to the home
agent equipment a binding update message including its first
regional care-of address and its IP home address and requesting it
to delete the record of the first regional care-of address so that
it retains only the record of the second regional care-of address
in corresponding relationship to the IP home address. The home
agent equipment can then send to the first mobile equipment a
binding acknowledgement type message after deleting the record of
the first regional care-of address.
[0034] The invention also proposes a mobility anchor point adapted
to implement a portion of a first handover method of the above
kind.
[0035] The invention further proposes a home agent equipment
adapted to implement a portion of a second handover method of the
above kind.
[0036] The invention is particularly well adapted to IPv6 (IP
version N.degree. 6) type networks. However, it relates equally to
IPv4 type networks supporting hierarchical mobility management.
[0037] Other features and advantages of the invention will become
apparent on reading the following detailed description and
examining the appended drawings.
IN THE DRAWINGS
[0038] FIG. 1 is a diagram of a portion of an IP network of the
invention using hierarchical mobility management.
[0039] FIG. 2 is a diagram of the main operations implementing
examples of first and second handover methods of the invention in
the IP network using hierarchical mobility management shown in FIG.
1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0040] The appended drawings may not only constitute part of the
description of the invention but also, if necessary, contribute to
defining the invention.
[0041] An object of the invention is to avoid the loss of data
packets and to shorten the phase during which a mobile
communication equipment (or mobile node) is no longer able to send
or receive data packets during handover between radio access
equipments connected (or attached) to mobility anchor equipments
(or points), which may be different, in an Internet Protocol (IP)
communication network using hierarchical mobility management (i.e.
comprising hierarchically organized points of presence (home agents
(HA) and mobility anchor points (MAP)).
[0042] An IPv6 type IP network is considered hereinafter by way of
nonlimiting example that supports the HMIPv6 (Hierarchical Mobile
IPv6) mobility management protocol, like its network equipments and
the mobile communication equipments (or mobile nodes) that can
connect to it. However, the invention applies equally to IPv4 type
IP networks, in particular by changing the messages used for
updating the binding caches.
[0043] The mobile communication equipments (referred to hereinafter
as mobile equipments (or nodes)) considered hereinafter by way of
nonlimiting example are personal digital assistants (PDA) equipped
with a communication module, for example of the WiFi or WiMAX--IEEE
802.1x type. However, the invention is not limited to this type of
mobile equipment. It relates to any type of mobile (or portable)
radio communication equipment capable of connecting to its home
(sub)network (or native subnetwork) or to other remote subnetworks
(or external subnetworks or visited networks) in order to exchange
data in the form of signals with another (fixed or mobile)
communication equipment or with a subnetwork, for example a mobile
telephone, a router or a laptop computer equipped with a
communication module.
[0044] An IP network using hierarchical mobility management that
can implement the handover methods of the invention is described
briefly first with reference to FIG. 1.
[0045] An IP network may be considered as a federation of subsets
of IP networks (or IP subnetworks), here represented by the balloon
labeled IGP (Interior Gateway Protocol) and generally comprising a
main subnetwork (for example a home (or native) network) of at
least one mobile node T1 to which other subnetworks (or access
networks) are connected.
[0046] In the present context, the expression "home (or native)
network" refers to the subnetwork to which a mobile node T1 is
usually connected, i.e. the subnetwork on which it has an IP home
(or native) address that corresponds to its prefix.
[0047] Each mobile node is associated with a home agent equipment
EA constituting its home agent, for example a router, belonging to
its home network. The IP home address of a mobile node is stored by
its home agent. The home agent equipment EA generally stores all
the position (and location) information in respect of the mobile
node associated with it, i.e. the mobility data concerning that
node, and provides a place of transit for data packets (or
datagrams) that must be transmitted to it when it is connected to a
remote IP subnetwork (or visited network) other than its home
network (as is the case in the FIG. 1 example).
[0048] The stored mobility data may include what the person skilled
in the art calls local and regional IP temporary addresses (or
complementary addresses or care-of addresses). These IP local
care-of address (LCoA) and IP regional care-of address (RCoA) are
unicast type routing addresses used respectively by the access
router R1 (to which a mobile node T1 is temporarily connected) and
the (mobility) anchor point P1 (to which the access router R1 is
connected and which is connected to the home agent EA of the mobile
node T1) to contact said mobile node T1. The home agent knows only
the regional care-of address (RCoA) of each mobile node T1
associated with it.
[0049] The IP local care-of addresses (LCoA) and IP regional
care-of addresses (RCoA) are determined by the mobile node T1 from
the (IP) address prefix of the access router to which it is
connected, for example by means of a standard IPv6 mechanism such
as a stateful or stateless autoconfiguration. When a mobile node T1
is connected to an access router R1 of a remote subnetwork, it must
inform its home agent EA in order for it to store its regional
care-of IP address RCoA in corresponding relationship to its IP
home address. To do this it uses a binding update procedure managed
by the mobility protocol (MIPv6). Using this IP regional care-of
address RCoA, a home agent EA is able to send a mobile node T1
associated with it data packets (or datagrams) that a calling node
T2 has sent to its IP home address. More precisely, each packet
sent to the IP home address of a mobile node T1 temporarily
connected to a remote subnetwork is intercepted by its home agent
EA and then forwarded via a tunnel passing through the anchor point
P1 to which its access router R1 is connected and through said
access router R1 to said mobile node T1 at the IP regional care-of
address RCoA associated (in its database) with its IP home
address.
[0050] The invention proposes two handover methods involving a
mobile first node T1 and a second node T2 (which may also be a
mobile node) between a first access router R1 to which the first
mobile node T1 is temporarily connected and which is connected to a
first anchor point P1 itself connected to the home agent EA of the
first mobile node T1 and a second access router R2 or R3 to which
the first mobile node T1 is directed and which is connected to the
first anchor point P1 (micromobility situation) or to a second
anchor point P2 itself connected to the home agent EA of the first
mobile node T1 (macromobility situation).
[0051] Both methods can be used in an IP network supporting
hierarchical mobility management, on the one hand when the first
mobile node T1 has set up an IP call with the second node T2 via
its home agent EA, the first anchor point P1 and the first access
equipment R1 and on the other hand when the first mobile node T1 is
roaming and has detected the second access equipment R2 or R3.
[0052] At this stage, the first mobile node T1 is configured with a
local care-of address LCoA-1 and a regional care-of address RCoA-1.
Moreover, the regional care-of address LCoA-1 is on the one hand
stored in the database of the home agent EA in corresponding
relationship to the IP home address and on the other hand known to
the first anchor point P1. Moreover, the local care-of address
LCoA-1 is known to the first access router R1 and to the anchor
point P1 (where it is stored in corresponding relationship to the
regional care-of address RCoA-1).
[0053] The first method of the invention is dedicated to
micromobility. It consists of a combination of three successive
steps described in detail hereinafter with reference to FIG. 2.
[0054] As shown in FIG. 2, the operations of the first method are
grouped together by a brace M1P beginning at the two-way arrow F9
and ending at the arrow F22.
[0055] The arrows F1 to F8 represent the standard connection phase
CP well known to the person skilled in the art during which the
first mobile node T1 connects to a first access router R1 belonging
to a first access subnetwork connected to the home network
containing the home agent EA of said first mobile node T1 via a
first mobility anchor point P1.
[0056] The arrow F1 represents a step during which the first access
router R1 sends the first mobile node T1 a router advertisement
(RA) type message including its address prefix (or network address)
and preferably the address of the anchor point to which it is
connected, generally in broadcast mode and via each of the
interfaces of the access router R1.
[0057] On receiving this message, the first mobile node T1 extracts
the address prefix from it in order to construct a first local
care-of address LCoA-1 and a first regional care-of address RCoA-1,
for example using a stateless autoconfiguration procedure
AutoConf.
[0058] The first mobile terminal T1 then generates a local binding
update message including its first local care-of address LCoA-1 and
its first regional care-of address RCoA-1 and sends the message to
the first anchor point P1 (F2) to which the first access router R1
is connected in order for it to store these addresses. The protocol
used in this step is preferably HMIPv6.
[0059] On receiving this message, the first anchor point P1 stores
the first local care-of address LCoA-1 and the first regional
care-of address RCoA-1 in its database. It then generates a binding
acknowledgement message to the first mobile node T1 (F3) to inform
it that it has stored these addresses.
[0060] The first mobile node T1 then sends its home agent EA (F4) a
binding update message containing its first regional care-of
address RCoA-1 and its IP home address. On receiving this message,
the home agent EA stores the first regional care-of address RCoA-1
in its database in corresponding relationship to the IP home
address. It then generates a binding acknowledgement message to the
first mobile node T1 (F5) to inform it that it has stored its first
regional care-of address RCoA-1.
[0061] The first mobile node T1 now being registered with its home
agent EA and the first anchor point P1, data packets coming from a
second (possibly mobile) node T2 can be forwarded to it in the
conventional way via its home agent EA (F6), the first anchor point
P1 (F7) and the first access router R1 (F8).
[0062] It is important to note that the connection phase CP
described above is common to the first and second methods.
[0063] The first step i) of the first method of the invention is
represented in FIG. 2 by the arrows F9 and F10. The first mobile
node T1 is connected by a radio connection via a first interface to
the base station that is connected to the first access router R1
and has detected (F9) a second access router R2 that is also
connected to the first anchor point P1. If the first mobile node T1
is sufficiently close to the base station that is connected to the
second access router R2, it can set up a radio connection via a
second interface with that base station (F9) and therefore receive
(F10) router advertisement type messages transmitted by the second
access router R2 over each of its interfaces, which messages
include its address prefix (or network address) and the address of
the anchor points to which it is connected (here P1).
[0064] On receiving this message the first mobile node T1 extracts
the address prefix from it in order to construct its second local
care-of address LCoA-2 and its second regional care-of address
RCoA-2, for example using a stateless autoconfiguration procedure
AutoConf.
[0065] In a second step ii) (arrows F11 to F16), there are
communicated to the first anchor point P1 the second local care-of
address LCoA-2, the first regional care-of address RCoA-1 and an
information bit (S) whose value indicates double temporary
addressing, in order for the first anchor point P1 to store this
second local care-of address LCoA-2 in corresponding relationship
to the first regional care-of address RCoA-1 and then forward
packets intended for the first mobile node T1 to the first access
router R1 and the second access router R2 designated by the first
local care-of address LCoA-1 and the second local care-of address
LCoA-2.
[0066] To do this, the first mobile node T1 can send the first
anchor point P1 (F11) a local binding update type message
containing its second local care-of address LCoA-2, its first
regional care-of address RCoA-1 and the information bit S whose
value indicates double temporary addressing, for example. This
information bit S is a data bit placed in the "reserved" field of a
local binding update type message, for example. A value of S equal
to 1 indicates double temporary addressing, for example. The
protocol used in this step is preferably HMIPv6.
[0067] On receiving this message, the first anchor point P1
analyzes the value of the information bit S and if it is equal to 1
(for example) records the second local care-of address LCoA-2 in
corresponding relationship to the first regional care-of address
RCoA-1 in its database. It then generates a binding acknowledgement
type message to the first mobile node Ti (F12) to inform it that it
has made a record of the double temporary addressing.
[0068] The first anchor point P1 can then temporarily forward
packets addressed to the first mobile node T1 not only to the first
access router R1 but also to the second access router R2, both of
which routers are designated by the first local care-of address
LCoA-1 and the second local care-of address LCoA-2. This double
transmission of the same data packets is indicated in FIG. 2 by the
arrows F13 to F16. More precisely, the packets received by the
first anchor point P1 from the home agent EA and addressed to the
first mobile node T1 are on the one hand forwarded (F13) to the
first access router R1 for it to communicate them (F14) to the
first mobile node T1 and on the other hand forwarded (F15) to the
second access router R2 for it to communicate them (F16) to the
same first mobile node T1. This is possible because the first
mobile node T1 is already connected to the first and second access
routers R1 and R2 via its first and second interfaces and because
the exchange of binding update type messages means that a tunnel
between the first mobile network T1 and the first anchor point P1
through the second access router R2 has already been created.
[0069] For the first mobile node T1 to be able to exchange data
with the first and second access routers R1 and R2 it is necessary
on the one hand for it to have two dialog logical radio interfaces
(see above), possibly coupled to the same send/receive antenna, and
for it to be capable of integrating an information bit S into a
field of a local binding update type message. The mobility anchor
points must also have a control device adapted to analyze the
information bit S and to store temporarily two local care-of
addresses LCoA-1 and LCoA-2 in corresponding relationship to the
same regional care-of address RCoA-1 in order to be able to
transfer identical data in parallel to the two access routers
designated by these two local care-of addresses LCoA-1 and LCoA-2
when the value of the information bit S that accompanies a second
local care-of address LCoA-2 and a first regional care-of address
RCoA-1 indicates double temporary addressing.
[0070] The mobility anchor point control device of the invention
may take the form of electronic circuits, software (or electronic
data processing modules) or a combination of circuits and
software.
[0071] In a third step iii) (arrows F17 to F22), the handover is
finalized first by disconnecting the first mobile node T1 from the
first access router R1. To do this, the stored first local care-of
address LCoA-1 of the first mobile node T1 is deleted at the first
anchor point P1 in order for the latter to receive data packets (or
datagrams) addressed to it only from the second access router
R2.
[0072] The first mobile node T1 then generates a local binding
update type message to the first anchor point P1 (F18) including
its first local care-of address LCoA-1, its first regional care-of
address RCoA-1 and data requesting the deletion of the record of
these addresses. This data may be the "lifetime" field, for
example, a value of 0 in which requires elimination of the record
of these addresses. The protocol used in this substep is preferably
HMIPv6.
[0073] On receiving this message, the first anchor point P1 deletes
from its database the first local care-of address LCoA-1 stored in
corresponding relationship to the first regional care-of address
RCoA-1 itself stored in corresponding relationship to the second
local care-of address LCoA-2. It then generates a binding
acknowledgement type message to the first mobile node T1 (F19) in
order to inform it that it has deleted the record of its old first
local care-of address LCoA-1.
[0074] The first mobile node T1 now being stored at the first
anchor point P1 with its second local care-of address LCoA-2 and
its first regional care-of address RCoA-1, data packets coming from
a second (possibly mobile) node T2 are now forwarded to it in the
conventional way via its home agent EA (F20), the first anchor
point P1 (F21) designated by the first regional care-of address
RCoA-1 and the second access router R2 (F22) designated by the
second local care-of address LCoA-2.
[0075] The second method of the invention is dedicated to
macromobility. It consists in a combination of four successive
steps described in detail hereinafter with reference to FIG. 2.
[0076] As shown in FIG. 2, the operations of the second method are
grouped together by a brace M2P starting at the two-way arrow F23
and ending at the arrow F40.
[0077] The first step i) of the second method begins on the one
hand when the first mobile node T2 has been stored at its home
agent EA, from a first anchor point P1 and a first access router R1
(i.e. after the connection phase CP described above (arrows F1 to
F8) has been effected) and on the other hand when the first mobile
node T1 has detected (F23) a second access router R3 that is
connected to a second anchor point P2 that is in turn connected to
the home agent EA. As previously indicated, if the first mobile
node T1 is sufficiently close to the base station that is connected
to the second access router R3, it can set up a radio connection
via a second interface with the base station (F23) and therefore
receive (F24) router advertisement type messages transmitted by the
second access router F3 over each of its interfaces that include
its address prefix (or network address) and preferably the address
of the anchor point to which it is connected.
[0078] On receiving this message, the first mobile node T1 extracts
the address prefix from it in order to construct a second local
care-of address LCoA-2 and a second regional care-of address
RCoA-2, for example using a stateless autoconfiguration procedure
AutoConf.
[0079] In a second step ii) (arrows F25 and F26), the second local
care-of address LCoA-2 and the second regional care-of address
RCoA-2 are communicated to the second anchor point P2 in order for
it to store them in corresponding relationship to each other in its
database.
[0080] To do this, the first mobile node T1 can generate a binding
update type message to the second anchor point P2 (F25) to which
the second access router R3 is connected, this message including
its second local care-of address LCoA-2 and its second regional
care-of address RCoA-2, in order for it to store them in its
database. The protocol used in this substep is preferably
HMIPv6.
[0081] On receiving this message, the second anchor point P2 stores
the second local care-of address LCoA-2 and the second regional
care-of address RCoA-2 in its database in corresponding
relationship to each other. It then generates a binding
acknowledgement type message to the first mobile node T1 (F26) in
order to report to it that it has stored them.
[0082] In a third step iii) (arrows F27 to F34), there are
communicated to the home agent EA the second regional care-of
address RCoA-2, the IP home address of the first mobile node T1,
and an information bit (S) having a value indicating double
temporary addressing in order for it to store the second regional
care-of address RCoA-2 in corresponding relationship to the IP home
address and then forward packets addressed to the first mobile node
T1 to the first and second anchor points P1 and P2 that are
designated by the first and second regional care-of addresses
RCoA-1 and RCoA-2 stored in corresponding relationship to the IP
home address.
[0083] To do this, the first mobile node T1 can send its home agent
EA (F27) a binding update type message, for example, containing its
second regional care-of address RCoA-2, its IP home address and the
information bit (S) whose value indicates temporary double
addressing. As in the first method, this information bit S is a
data bit that is placed in the "reserved" field in a binding update
type message, for example. For example, a value of S equal to 1
indicates double temporary addressing. The protocol used in this
substep is preferably HMIPv6.
[0084] On receiving this message, the home agent EA analyzes the
value of the information bit S and if it is equal to 1 (for
example) stores the second regional care-of address RCoA-2 in its
database in corresponding relationship to the IP home address which
is itself stored in corresponding relationship to the first
regional care-of address RCoA-1. It then generates a binding
acknowledgement type message to the first mobile node T1 (F28) in
order to inform it that it has made a record of the double
temporary addressing.
[0085] The home agent EA can then temporarily forward packets
addressed to the first mobile node T1 not only to the first anchor
point P1 but also to the second anchor point P2, both of which are
designated by the first and second regional care-of addresses
RCoA-1 and RCoA-2. This double forwarding of the same data packets
is indicated in FIG. 2 by the arrows F29 to F34. More precisely,
packets received by the home agent EA and addressed to the first
mobile node T1 are on the one hand forwarded (F29) to the first
anchor point P1 in order for it to communicate them to the first
access router R1 (F30) and for the latter then to communicate them
to the first mobile node T1 (F31) and on the other hand forwarded
(F32) to the second anchor point P2 for it to communicate them to
the second access router R3 (F33), in order for the latter then to
communicate them to the same first mobile node T1 (F34). This is
possible because the first mobile node T1 is already connected to
the first and second access routers R1 and R3 via its first and
second interfaces and because the exchange of binding update type
messages has created a tunnel between the first mobile node T1 and
the second anchor point P2 through the second access router R3.
[0086] As indicated above, for the first mobile node T1 to be able
to exchange data with the first and second access routers R1 and R2
it must on the one hand have two dialog logic radio interfaces,
possibly coupled to the same send/receive antenna, and on the other
hand be able to integrate an information bit S into a binding
update type message field. The home agent EA must also include a
control device capable of analyzing the information bit S and
temporarily storing two regional care-of addresses RCoA-1 and
RCoA-2 in corresponding relationship to the same IP home address in
order to be able to transfer identical data in parallel to the two
anchor points P1 and P2 designated by these two regional care-of
addresses RCoA-1 and RCoA-2 when the value of the information bit S
that accompanies a second regional care-of address RCoA-2 and an IP
home address indicates double temporary addressing.
[0087] The control device of a home agent EA of the invention can
take the form of electronic circuits, software (or electronic data
processing) modules or a combination of circuits and software.
[0088] In a fourth step iii) (arrows F35 to F40), handover is
finalized first by disconnecting the first mobile node T1 from the
first access router R1. To do this, the record of the first
regional care-of address RCoA-1 of the first mobile node T1 is
deleted in the home agent EA in order for the latter to receive
data packets (or datagrams) addressed to it only from the second
anchor point P2 via the second access router R2.
[0089] The first mobile node T1 then generates a binding update
type message to the home agent EA (F36) including its first
regional care-of address RCoA-1, its IP home address and
information requesting the deletion of the record of these
addresses. As in the first method, this information data can be in
the "lifetime" field, for example, a value of 0 in which requires
elimination of the stored addresses. The protocol used in this
substep is preferably HMIPv6.
[0090] On receiving this message, the home agent EA eliminates from
its database the first regional care-of address RCoA-1 stored in
corresponding relationship to the IP home address itself stored in
corresponding relationship to the second regional care-of address
RCoA-2. It then generates a binding acknowledgement type message to
the first mobile node T1 (F37) in order to inform it that it has
deleted the stored old first regional care-of address RCoA-1.
[0091] The first mobile node T1 now being stored in its home agent
EA with its second regional care-of address RCoA-2, data packets
coming from a second (possibly mobile) node T2 are not forwarded in
the conventional way via its home agent EA (F38), the second anchor
point P2 (F39) designated by the second regional care-of address
RCoA-2 and the second access router R3 (F40) designated by the
second local care-of address LCoA-2 (stored in R3 after the substep
F25).
[0092] It is important to note that the first and second methods
described above may coexist in the same IP network using
hierarchical mobility management in order to cover micromobility
and macromobility situations. This requires that the mobile nodes
be adapted to integrate an information bit (S) indicating double
temporary addressing, both in local binding update type messages
and in binding update type messages. This further requires home
agents adapted in accordance with the invention to coexist with
mobility anchor points also adapted in accordance with the
invention.
[0093] The invention is not limited to the handover method, home
agent equipment and mobility anchor point embodiments described
above by way of example only and encompasses all variants that the
person skilled in the art might envisage that fall within the scope
of the following claims.
* * * * *